Fire fighting water pumps are used when the local public utility or an engineered fire water pond cannot supply enough pressure to meet the hydraulic design requirements of the sprinkler system. They are typically activated during annual testing and must provide water at high pressure with a specified flow.
The pump must be sized correctly and have adequate power reserve to avoid cavitation, especially when ramping up from the lowest duty point of the power curve.
Power
Fire fighting water pumps use electrical power provided from a utility connection, generator or other approved power source. This power turns an electric motor that then spins the shaft to deliver water to systems within the building.
These fire fighting water pumps have a variety of features including twin impellers that create more pressure which helps to reduce cavitation. Additionally, the nozzles on these fire fighting water pumps are adjustable to control flow and pressure.
The fire fighting water pump system is a vital component of the fire sprinkler system, as it provides the additional pressure needed to meet the demand of a building or space. These fire pumps are used in high-rise buildings and expansive warehouse spaces to ensure the fire sprinklers can reach all areas of the building. The fire fighting water pump is activated when the fire sprinkler system’s water pressure drops below a certain threshold. Two important specs to understand are PSI and GPM. PSI refers to the pressure per square inch, while GPM relates to how much water is delivered by the fire fighting water pump.
Design
Fire fighting water pumps supply water to sprinkler systems at a fixed pressure that helps mitigate fires. They must be sized for the sprinkler system demand and for the power consumed by the pumping system. A factory-certified test curve must be available so that the pump can be properly sized.
The design of the building must be considered for a number of reasons when sizing a fire pump. For example, a high-rise will require more power because of gravity and the need to push water to the top floors of the building. A hazard analysis should also be completed to determine if there are any special hazards that may require more water pressure than required for the fire sprinkler system.
The design should also consider the electrical power requirements, which may vary depending on the building infrastructure and if a backup generator is used. The fire-protection and plumbing engineers should coordinate to provide for proper drainage, ventilation, and access for diesel fuel tank refueling.
Flow
The rate of flow (GPM) and pressure of a fire fighting water pump are important metrics to keep in mind. Both can have a big impact on your ability to fight fires safely and effectively.
For example, if your building’s water supply is too low in pressure to meet the hydraulic design requirements of the standpipe system, it can be necessary to install an additional fire pump with higher GPM and pressure capabilities. This is a major undertaking that requires extensive planning and coordination between the pump manufacturer, local fire marshal, fire protection specialist and installers to ensure a successful installation.
During the acceptance testing of a fire pump, both the suction and discharge pressures are measured to confirm that the pumps can perform as designed during a fire emergency. To achieve this, the fire pumps must be able to reach a minimum of churn at full capacity without exceeding a maximum discharge pressure. This is determined using a pump performance curve, which plots the flow on the “x” axis against the net pressure produced by the pump at various conditions between churn and maximum flow.
Noise
As with any equipment, fire pumps must undergo a series of inspections to ensure they will work as expected during a real emergency. These include weekly or monthly no-flow tests and an annual frequency testing with flow. This puts the entire system through its paces and allows professionals to look for any issues that may arise in the future.
One such issue is called water hammer, a banging noise that occurs when a valve closes quickly in the system, creating a sudden surge of pressure. This can damage piping and cause problems with the overall operation of the fire suppression system. To reduce this problem, firefighters sometimes use slow-closing valves or air chambers in the piping to absorb the shock.
It’s hard to pin down a specific decibel level that a pump should be at. It’s largely subjective and will depend on the setting or location where the pump is used. However, proper maintenance can help to keep the pump at an acceptable noise level.